Meconium aspiration syndrome: Difference between revisions
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*Supportive care: see [[newborn resuscitation]] | *Supportive care: see [[newborn resuscitation]] | ||
**Adequate oxygenation and ventilation | **Adequate oxygenation and ventilation | ||
***Supplemental oxygen to keep saturation >99% and PaO2 55-90 | ***Supplemental [[oxygen]] to keep saturation >99% and PaO2 55-90 | ||
***Assisted ventilation with CPAP if FiO2 exceeds 0.4 to 0.5 | ***Assisted ventilation with [[CPAP]] if FiO2 exceeds 0.4 to 0.5 | ||
***High frequency oscillatory ventilation or ECMO for those who fail conventional mechanical ventilation | ***High frequency oscillatory ventilation or ECMO for those who fail conventional mechanical ventilation | ||
***Goal PaCO2 50-55 mmHg | ***Goal PaCO2 50-55 mmHg | ||
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***Umbilical lines to monitor blood gases and BP | ***Umbilical lines to monitor blood gases and BP | ||
**Correct metabolic abnormalities | **Correct metabolic abnormalities | ||
*Empiric antibiotics while awaiting culture results (because of difficulty differentiating between pneumonia initially) | *Empiric [[pediatric antibiotics|antibiotics]] while awaiting culture results (because of difficulty differentiating between pneumonia initially) | ||
*Surfactant administration for severe disease requiring mechanical ventilation, FiO2>0.5, and mean airway pressure >10-12 | *Surfactant administration for severe disease requiring mechanical ventilation, FiO2>0.5, and mean airway pressure >10-12 | ||
Revision as of 18:10, 6 October 2019
Background
- Presentation ranges from mild respiratory distress to life-threatening respiratory failure
- Incidence is 2-10% of infants born through MSAF (meconium-stained amniotic fluid)
- Thought to be associated with fetal hypoxia and post-term delivery
- Causes hypoxemia and acidosis via airway obstruction, chemical irritation/inflammation, infection, and surfactant inactivation
- Associated with persistent pulmonary hypertension of the newborn (PPHN)
Clinical Features
- Usually develop symptoms within 15 minutes after birth
- Tachypnea
- Cyanosis
- Accessory muscle use (intercostal/subxiphoid retractions, paradoxical breathing, grunting, nasal flaring)
- Barrel-shaped chest
- Rales and rhonchi on lung auscultation
- Pneumothorax
- Pneumomediastinum
Differential Diagnosis
- Sepsis
- Pneumonia
- Delayed transition from fetal circulation
- Pneumothorax
- Pulmonary edema
- Blood aspiration
- Pulmonary hypertension
- Congenital heart disease
Newborn Problems
- Newborn resuscitation
- Hypoxia
- Primary apnea
- Secondary apnea
- Hypothermia
- Hypoglycemia
- Meconium aspiration syndrome
- Anemia (abruption)
- Infant scalp hematoma
- Transient tachypnea of the newborn
- Respiratory distress syndrome
- Congenital pneumonia
- Congenital heart disease
- Neonatal sepsis
- Pneumothorax
- Pulmonary hypertension
Evaluation
Workup
- CXR
- Streaky, linear densities
- Hyperinflated lungs and flattened diaphragm
- Diffuse patchy opacities (may appear similar to RDS if severe)
- ABG
- Echocardiography
- Blood and sputum cultures
Diagnosis
- Clinical diagnosis based on the following:
- Evidence of meconium on infant
- Respiratory distress shortly after birth
- Characteristic CXR findings
- If intubation required, meconium visualized in trachea
- Ways to differentiate between other causes of respiratory distress in a neonate:
- Transient tachypnea of the newborn is more common in late preterm infants (34-37 weeks) and RDS in preterm infants, whereas MAS more common in postmature infants (>41 weeks)
- Delayed transition from fetal circulation symptoms improve more quickly than those of MAS
- Congenital cyanotic heart disease is differentiated by physical exam (murmurs, hepatomegaly), CXR (cardiac size/shape), and echocardiogram (cardiac anatomy and function)
Management
- Supportive care: see newborn resuscitation
- Adequate oxygenation and ventilation
- Maintain blood pressure and perfusion
- Umbilical lines to monitor blood gases and BP
- Correct metabolic abnormalities
- Empiric antibiotics while awaiting culture results (because of difficulty differentiating between pneumonia initially)
- Surfactant administration for severe disease requiring mechanical ventilation, FiO2>0.5, and mean airway pressure >10-12
Disposition
- Admit to NICU
Prevention
- Fetal heart rate monitoring intrapartum to reduce risk of fetal hypoxia
- Induction of labor after 41 weeks gestation to reduce postmature delivery
- Amnioinfusion with isotonic fluid to dilute thick meconium is NOT routinely recommended